1. Field of the Invention
The present invention relates to an air-bearing head slider of an electromagnetic transducer in which at least two rails for generating a floating force are provided on a surface opposed to a magnetic recording medium in the direction of an air flow generated by the rotation of the magnetic recording medium.
2. Description of the Related Art
Recently, there is a demand for downsizing electromagnetic disk units. In the case of an air-bearing electromagnetic head slider, the floating height has been reduced so as to accomplish high density recording. When the floating height of the electromagnetic head slider is reduced, it becomes necessary to stabilize an amount of floating height. Even when the dust is rising in the head gap, it is necessary for the electromagnetic head to be kept floating in a stable manner. On the other hand, in order to enhance the portability and reliability, it is necessary to enhance the shock resistance property.
At present, the most widely used electromagnetic head slider is the one referred to as a "Winchester" type. The Winchester type electromagnetic head slider is provided with two linear rails, and an inclined surface is formed on the air flow entry side of a floating surface of each rail. This electromagnetic head slider has a circumferential speed dependency, so that an amount of floating height of the head is increased in accordance with an increase of circumferential speed with respect to the rotating media.
On the other hand, where a rotary actuator is used, the seeking operation of the electromagnetic head is conducted by a circular arc motion of the actuator. Thus, a YAW angle is changed in accordance with a position of the head with respect to the recording medium in the radial direction, so that an amount of floating height is also changed by this YAW angle.
Therefore, conventionally, the YAW angle dependency of the rotary actuator and the circumferential speed dependency of the magnetic head slider are combined in such a manner that an amount of floating height is stabilized.
Stabilization of the head floating height is not limited to the approach described above. For example, in Japanese Unexamined Patent Publication (Kokai) No. 60-101781 and U.S. Pat. No. 5,062,017 disclose a technique in which the stabilization of the floating height is realized by devising a configuration of the electromagnetic head slider.
According to Japanese Unexamined Patent Publication (Kokai) No. 4-228157, there is provided an electromagnetic head slider in which the configuration of the head slider is devised so as to reduce and stabilize the amount of the floating height, the electromagnetic head slider being characterized in that: a shallow groove is formed between the rails; a groove width extending section is formed in at least a portion of the groove, in which the groove width is increased when a view is taken from the air entry side to the air delivery side; and a negative pressure is generated in the groove so that the magnetic head slider is attracted to the magnetic recording medium side.
In the above-mentioned conventional negative pressure slider, a pair of rails for generating a floating force are provided on a surface opposed to the magnetic recording medium in the direction of an air flow generated by the rotation of a magnetic recording medium. Inclined surfaces are respectively provided on the floating surfaces of the rails on the air flow entry side.
A shallow groove is formed between these rails. In the groove, there is provided a groove width extending section, the width of which is extended when a view is taken from the air entry side to the air delivery side.
In the air-bearing electromagnetic head slider constructed in the manner described above, when an air flow is generated by the rotation of a magnetic recording medium in the direction on the floating surfaces of the rails, a floating force is generated in which the electromagnetic head slider is moved in a direction away from the magnetic recording medium. That is to say, a floating force is generated so that the electromagnetic head slider is moved upward. At the same time, in the groove extending section of the groove, the flowing air is expanded, and a negative pressure is generated, by which the electromagnetic head slider is attracted to the magnetic recording medium side, that is, the magnetic head slider is moved downward. Therefore, the electromagnetic head slider floats to a height at which both forces are balanced. Then the electromagnetic head slider stops at the balanced position.
However, in the above construction, the inclination angles of the inclined surfaces of the electromagnetic head slider are so small in the same manner as those of the inclination surfaces of other electromagnetic head sliders, and the lengths of the inclined surfaces in the air flow direction are small.
Therefore, when the dust adheres to an air flow entry portion of the electromagnetic head slider (especially on the floating surface of the rail), the amount of floating height of the electromagnetic head slider is greatly affected by a negative pressure generated in the rear of the adhering dust (in the downstream), so that the amount of floating height is reduced, which causes a problem in the viewpoint of stability of the floating height. Further, concerning the shock resistance property, the above construction is not competent.